These files are part of the dataset
"Historical Land Use for the U.S. 1940-2015: Class Counts",
contained in the dataverse  HISDAC-US: Historical Settlement Data Compilation for the United States  
(https://dataverse.harvard.edu/dataverse/hisdacus).

Reference:
Mc Shane, Caitlin M.;Uhl, Johannes H.; Leyk, Stefan 2021,  "Historical Land Use for the U.S. 1940-2015",
https://doi.org/10.7910/DVN/I30REZ, Harvard Dataverse.

The gridded surfaces (*.tif) contained in the counts.tar.gz archive represent number of records within grid cells of 250x250m, for each of the six
land use themes on a mid-decadal scale (i.e., 1940 indicated in the file name as _1940_to_1944 which means that values up to 1944 are summed up). 
Moreover, the layer for 2016 includes all georeferenced records from the underlying ZTRAX dataset with a land use attribute, regardless the value 
or availability of the built year attribute. Thus, **2016.tif represents the spatial distribution of theme specific land use for all property locations 
approximately in 2016, when the underlying ZTRAX data were compiled.


Historical Land Use for the U.S. 1940-2015 (Class Counts)
Abbreviations and explanations:
Geo-Referenced:		Records are georeferenced if an explicit latitude and longitude is provided in ZTRAX.
Missing Grid-ID:	Records without an explicit latitude and longitude, which could not be grid-indexed.
.tar.gz 'A': 		Agriculture
.tar.gz 'C': 		Commercial
.tar.gz 'I': 		Industrial
.tar.gz 'RC': 		Recreational
.tar.gz 'RI': 		Residential-Income
.tar.gz 'RO': 		Residential-Owned
Grid Cell Value:	The number of records with a land use descriptiong for the individual theme
				

Data source: Zillow Transaction and Assessment Dataset (ZTRAX) (c) Zillow Inc.
Spatial resolution: 250m
Coordinate reference system:
USA Contiguous Albers Equal Area Conic USGS version (SR-ORG:7480)
https://spatialreference.org/ref/sr-org/usa_contiguous_albers_equal_area_conic_usgs_version-2/
Proj4: +proj=aea +lat_1=29.5 +lat_2=45.5 +lat_0=23.0 +lon_0=-96 +x_0=0 +y_0=0 +ellps=GRS80 +datum=NAD83 +units=m +no_defs

Contact:
Stefan Leyk
Department of Geography
University of Colorado Boulder
GUGG 110, 260 UCB 
Boulder, CO 80309-0260, United States of America
stefan.leyk@colorado.edu